Method for producing low-chlorine polybiphenyl sulfone polymers

ABSTRACT

The present invention relates to a process for the production of low-chlorine-content polybiphenyl sulfone polymers, to the polybiphenyl sulfone polymers obtainable in this way, to polybiphenyl sulfone polymers with less than 800 ppm content of organically bonded chlorine, to thermoplastic molding compositions and moldings, fibers, films, membranes, or foams comprising the polybiphenyl sulfone polymers mentioned, and also to their use for the production of moldings, of fibers, of films, of membranes, or of foams.

The present invention relates to a process for the production oflow-chlorine-content polybiphenyl sulfone polymers, to the polybiphenylsulfone polymers obtainable in this way, to polybiphenyl sulfonepolymers with less than 800 ppm content of organically bonded chlorine,to thermoplastic molding compositions and moldings, fibers, films,membranes, or foams comprising the polybiphenyl sulfone polymersmentioned, and also to their use for the production of moldings, offibers, of films, of membranes, or of foams.

Polybiphenyl sulfone polymers belong to the polyarylene ethers group,and therefore to the class of engineering thermoplastics. Polybiphenylsulfone polymers have not only high heat resistance but superior notchedimpact resistance and excellent fire performance, as described by way ofexample in: E. M. Koch, H.-M. Walter, Kunststoffe 80 (1990) 1146; E.Daring, Kunststoffe 80, (1990) 1149; and N. Inchaurondo-Nehm,Kunststoffe 98, (2008) 190.

The production of polybiphenyl sulfone polymers is disclosed by way ofexample in DE 1957091 and EP 000361. WO 2000/018824 discloses a processfor the production of polybiphenyl sulfone polymers having low contentof cyclic oligomers. EP 1272547 describes polybiphenyl sulfone polymerswith a particularly low level of intrinsic color, obtained viacondensation of the monomers 4,4′-dihydroxybiphenyl and4,4′-dichlorodiphenyl sulfone in the presence of fine-particle potash.

The prior art usually uses equimolar amounts of the starting materials.However, the resultant content of organically bonded chlorine in thepolybiphenyl sulfone polymers from known processes is too high for manyapplications and often fails to comply with fire-protectionrequirements. Chlorine contents of less than 1000 ppm are often demandedfor applications in the electronics sector, e.g. switches, casings,foils. The known polybiphenyl sulfone polymers moreover have highresidual solvent content.

The reaction of the abovementioned monomers in N-methylpyrrolidone (NMP)as solvent is also known per se, for example from EP 0 347 669. NMP hasinter alia a number of advantages in terms of process technology. By wayof example, the monomers and the potassium carbonate used as base havegood solubility in NMP; it is moreover possible to conduct a reactionwithout any additional entrainer for the water produced by the reaction.Process-technology reasons therefore, make it desirable that thepolycondensation reaction for the production of polybiphenyl sulfonepolymers is carried out in NMP as solvent.

The abovementioned monomers have extremely high reactivity in NMP assolvent. In many instances when NMP is used as solvent, this generatesproblems in control of intrinsic viscosity (IV), which characterizes thedegree of polymerization.

The person skilled in the art is aware from J. E. McGrath et al.,Polymer 25 (1984), 1827 of a method of controlling molecular weight inthe condensation of polyarylene sulfones based on bisphenol A.Commercial polyarylene ethers, e.g. Sumika Excel®, have mainly chlorineend groups. No process hitherto disclosed produces polybiphenyl sulfonepolymers in NMP by using an excess of the aromatic dihydroxy compound.

The tensile strain at break of the polybiphenyl sulfone polymers knownfrom the prior art is moreover in many instances inadequate; the notchedimpact resistance of these polymers is unsatisfactory, and they oftenhave inadequate flow behavior at low shear rates.

The polybiphenyl sulfone polymers of the present invention should havethe aforementioned disadvantages to a relatively minor degree, if atall. A particular object of the present invention was to provide aprocess which can produce polybiphenyl sulfone polymers having theproperties mentioned with good control of molecular weight. Thepolybiphenyl sulfone polymers should in particular have low viscosity atlow shear rate and have good flow within a mold.

Another object of the present invention was to provide polybiphenylsulfone polymers which have superior mechanical properties, inparticular high tensile strain at break and high notched impactresistance, and which comprise low content of polymer-bonded chlorineand which moreover have less residual solvent content than the priorart. The prior art has not hitherto disclosed any polybiphenyl sulfonepolymers with less than 800 ppm content of polymer-bonded chlorine.

The present object is achieved via a process for the production ofpolybiphenyl sulfone polymers comprising according to step (a) thereaction of component (a1) composed of at least one aromatic dihydroxycompound and (a2) 4,4′-dichlorodiphenyl sulfone, where component (a1)comprises 4,4′-dihydroxybiphenyl and the reaction is carried out with amolar excess of component (a1) in a solvent comprisingN-methylpyrrolidone, and also via the resultant polybiphenyl sulfonepolymers. Preferred embodiments can be found in the claims and in thedescription below. Combinations of preferred embodiments are within thescope of the invention.

The term polybiphenyl sulfone polymer is intended to mean polyaryleneether sulfones which comprise 4,4′-dihydroxybiphenyl as monomer unit.Polybiphenyl sulfone itself is also known as polyphenyl sulfone,abbreviated to PPSU, and is composed of the following monomer units:4,4′-dichlorodiphenyl sulfone and 4,4′-dihydroxybiphenyl.

For the purposes of the present invention, in order to characterize thestructure of the polybiphenyl sulfone polymer, reference is made to themonomer units used. It is obvious to the person skilled in the art thatthe monomer units are present in reacted form within the polymer, andthat the reaction of the monomer units via nucleophilic aromaticpolycondensation takes place with theoretical elimination of one unit ofhydrogen halide as leaving group. The structure of the resultant polymeris therefore independent of the precise nature of the leaving group.

The reaction of the components (a1) and (a2) to form a polybiphenylpolymer is known per se to the person skilled in the art, in terms ofthe temperature, the solvent and the duration. The reaction of thestarting compounds (a1) and (a2) is carried out at a temperature of from80 to 250° C., preferably from 100 to 220° C., where the boiling pointof the solvent provides the upper temperature limit. The reaction timeis preferably from 2 to 12 h, in particular from 3 to 8 h.

The use of an excess of component (a1) makes a contribution to areduction in content of polymer-bonded chlorine, in particular at highconversions. The molar ratio of component (a1) to (a2) used ispreferably from 1.005 to 1.2, in particular from 1.005 to 1.1. In oneparticularly preferred embodiment, the molar ratio of component (a1) to(a2) is from 1.005 to 1.08, in particular from 1.01 to 1.05, veryparticularly preferably from 1.015 to 1.04. This enables particularlyeffective control of molecular weight.

It is advantageous for the present invention that the reactionconditions are selected in such a way that conversion (C) is at least90%, in particular at least 95%, particularly preferably at least 98%.For the purposes of the present invention, conversion C is the molarproportion of reactive groups (i.e. hydroxy and chloro groups) that havebeen reacted. The final product has relatively broad molecular weightdistribution, where appropriate inclusive of oligomers, and the endgroups here are either chloro or hydroxy groups, or, in the event offurther reaction, alkyl- or aryloxy groups, corresponding arithmeticallyto the difference from 100% conversion.

Surprisingly, it has been found that the content of polymer-bondedchlorine observed is particularly low when the solvent used comprisesN-methylpyrrolidone. N-Methylpyrrolidone is very particularly preferredas sole solvent. N-Methylpyrrolidone at the same time contributes tohigh conversion of components (a1) and (a2), since the reaction of themonomers used according to the invention proceeds particularlyefficiently.

According to the invention, component (a1) is composed of at least onearomatic dihydroxy compound, and comprises 4,4′-dihydroxybiphenyl.Component (a1) can in particular comprise the following compounds:

-   dihydroxybenzenes, in particular hydroquinone and/or resorcinol;-   dihydroxynaphthalenes, in particular 1,5-dihydroxynaphthalene,    1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, and/or    2,7-dihydroxynaphthalene;-   dihydroxybiphenyls other than 4,4′-dihydroxybiphenyl, in particular    2,2′-dihydroxybiphenyl;-   bisphenyl ethers, in particular bis(4-hydroxyphenyl) ether and    bis(2-hydroxyphenyl) ether;-   bisphenyipropanes, in particular 2,2-bis(4-hydroxyphenyl)propane,    2,2-bis(3-methyl-4-hydroxyphenyl)propane, and/or    2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane;-   bisphenylmethanes, in particular bis(4-hydroxyphenyl)methane;-   bisphenylcyclohexanes, in particular    bis(4-hydroxyphenyl)-2,2,4-trimethylcyclohexane;-   bisphenyl sulfones, in particular bis(4-hydroxyphenyl) sulfone;-   bisphenyl sulfides, in particular bis(4-hydroxyphenyl) sulfide;-   bisphenyl ketones, in particular bis(4-hydroxyphenyl) ketone;-   bisphenylhexafluoropropanes, in particular    2,2-bis(3,5-dimethyl-4-hydroxyphenyl)hexafluoropropane; and/or-   bisphenylfluorenes, in particular 9,9-bis(4-hydroxyphenyl)fluorene.

Component (a1) preferably comprises at least 50% by weight, inparticular at least 60% by weight, particularly preferably at least 80%by weight, of 4,4′-dihydroxybiphenyl. It is very particularly preferablethat component (a1) is 4,4′-dihydroxybiphenyl.

For the purposes of the present invention, solvents that can be used ina mixture with N-methyl-2-pyrrolidone (NMP) are aprotic polar solventsother than NMP. The boiling point of suitable solvents here is in therange from 80 to 320° C., in particular from 100 to 280° C., preferablyfrom 150 to 250° C. Particularly suitable polar aprotic solvents arehigh-boiling-point ethers, esters, ketones, asymmetrically halogenatedhydrocarbons, anisole, dimethylformamide, dimethyl sulfoxide, andsulfolane. However, particular preference is given toN-methyl-2-pyrrolidone (NMP) as solvent.

The reaction of the components (a1) and (a2) preferably takes place inthe presence of a base (B), in order to increase reactivity with respectto the halogen substituents of the starting compounds (a2). It ispreferable to start from the abovementioned aromatic dihydroxy compounds(a1) and add a base (B) to produce their dipotassium or disodium salts,and react these with component (a1). The person skilled in the art isaware of suitable bases (B). Preferred bases (B) are in particularalkali metal carbonates.

The bases are preferably anhydrous. Particularly suitable bases areanhydrous alkali metal carbonate, preferably sodium carbonate, potassiumcarbonate, calcium carbonate, or a mixture thereof, very particularpreference being given to potassium carbonate. One particularlypreferred combination is N-methyl-2-pyrrolidone as solvent and anhydrouspotassium carbonate as base.

It has also proven advantageous for the purposes of step (a) to set theamount of the polybiphenyl sulfone polymer to from 10 to 70% by weight,preferably from 15 to 50% by weight, based on the total weight of themixture composed of polybiphenyl sulfone polymer and solvent.

In one preferred embodiment, during or after the reaction at least onearomatic organic monochloro compound is added as component (a3). It isbelieved that the aromatic organic monochloro compound acts as chainregulator. It is preferable that the reactivity of the aromatic organicmonochloro compound in the reaction is similar to that of component(a2).

Component (a3) is preferably an aromatic monochloro sulfone, inparticular monochlorodiphenyl sulfone. In one preferred embodiment, theexcess of component (a1) is compensated via the aromatic organicmonochloro compound (a3), which comprises one chloro group reactiveunder the conditions of the reaction of components (a1) and (a2).

The molar amount of component (a3) is preferably selected in such a waythat the product when the excess of the molar amount of component (a1)with respect to the molar amount of component (a2) divided by the molaramount of component (a3) is multiplied by two is from 0.98 to 1.02, inparticular from 0.99 to 1.01. Accordingly, 2*((a1)−(a2))/(a3) ispreferably from 0.98 to 1.02, in particular from 0.99 to 1.01, where(a1), (a2), and (a3) are the molar amounts used of the respectivecomponents.

It is preferable here that the product when the ratio ((a1)−(a2)/(a3))is multiplied by two is 1.

In another preferred embodiment, which can advantageously be linked tothe abovementioned embodiments, according to step (b), after step (a), areaction takes place with at least one aliphatic organic halogencompound. The result is further reaction of reactive hydroxy end groups,thus inhibiting degradation of the polymer chain.

Preferred aliphatic organic halogen compounds are alkyl halides, inparticular alkyl chlorides having linear or branched alkyl groups havingfrom 1 to 10 carbon atoms, in particular primary alkyl chlorides,particularly preferably methyl halide, in particular methyl chloride.

The reaction of step (b) is preferably carried out at a temperature offrom 90° to 160° C., in particular from 100° C. to 150° C. The durationcan vary widely and is usually at least 5 minutes, in particular atleast 15 minutes. The duration of the reaction of step (b) is preferablyfrom 15 minutes to 8 hours, in particular from 30 minutes to 4 hours.

Various methods can be used to add the aliphatic organic halogencompound. The amount added of the aliphatic organic halogen compound canmoreover be stoichiometric or an excess, and by way of example theexcess can be up to 5-fold. In one preferred embodiment, the aliphaticorganic halogen compound is added continuously, in particular viacontinuous introduction in the form of a gas stream.

It has proven advantageous, after step (a) and optionally step (b), tofilter the polymer solution. The result is to remove the salt contentformed in the polycondensation reaction, and also to remove any gelformed.

The present invention further provides polybiphenyl sulfone polymerswhich are obtainable according to the process of the invention, and alsopolybiphenyl sulfone polymers with less than 800 ppm content ofpolymer-bonded chlorine, in particular less than 700 ppm.

The polybiphenyl sulfone polymers of the invention preferably have lessthan 800 ppm content of polymer-bonded chlorine, in particular less than750 ppm, particularly preferably less than 700 ppm. The lower limit ofcontent of polymer-bonded chlorine is usually at least 400 ppm, inparticular at least 500 ppm, as a function of the process.

The chlorine content of the polymer that can be obtained corresponds tothe content of chloro end groups and for the purposes of the presentinvention is determined by means of atomic spectroscopy. For thepurposes of the present invention, the content of polymer-bondedchlorine is based in principle on the proportion by weight, and as analternative it can be stated in mg per kg of starting weight of thepolymer.

Polymer compositions obtainable by the process of the inventionparticularly preferably have less than 700 ppm content of polymer-bondedchlorine and at the same time less than 500 ppm content of residualsolvent.

Another feature of the polybiphenyl sulfone polymers of the invention istensile strain at break of more than 50% in the tensile test.

The present invention further provides thermoplastic moldingcompositions comprising a polybiphenyl sulfone polymer of the invention.

The thermoplastic molding compositions of the present invention can alsocomprise, alongside the polybiphenyl sulfone polymer of the invention,at least one polymer selected from polyarylene ether sulfones (otherthan the polybiphenyl sulfone polymers of the invention), in particularpolyether sulfone (PES) and/or polysulfone (PSU), or elsepolyetherimides, polyphenylene sulfides, polyether ether ketones,polyimides, or poly-p-phenylenes.

The molding compositions of the invention can moreover comprise fillers,in particular fibers, particularly preferably glass fibers. A personskilled in the art is aware of appropriate fillers.

To the extent that fillers are used, the preferred amount of these thenadded is from 5 to 150 parts by weight, based on 100 parts by weight ofpolymer.

In particular, the thermoplastic molding compositions of the inventioncan comprise any of the glass fibers that are known to the personskilled in the art and that are suitable for use in thermoplasticmolding compositions. Said glass fibers can be produced by the processknown to the person skilled in the art and can optionally besurface-treated. The glass fibers can have been equipped with a size inorder to improve compatibility with the matrix material, e.g. asdescribed in DE 10117715.

In one preferred embodiment, glass fibers of diameter from 5 to 15 μm,preferably from 7 to 13 μm, particularly preferably from 9 to 11 μm, areused.

The glass fibers incorporated can take the form either of chopped glassfibers or else of continuous-filament strands (rovings). The length ofthe glass fibers that can be used is generally and typically from 4 to 5mm prior to incorporation in the form of chopped glass fibers into thethermoplastic molding compositions. The average length of the glassfibers after processing of the same, for example via coextrusion, withthe other components, is usually from 100 to 400 μm, preferably from 200to 350 μm.

The molding compositions of the invention can comprise, as furthercomponent K, auxiliaries, in particular processing aids, pigments,stabilizers, flame retardants, or a mixture of different additives.Other examples of conventional added materials are oxidation retarders,heat stabilizers, UV stabilizers, lubricants and mold-release agents,dyes, and plasticizers.

The content of the further components K in the molding compositions ofthe invention is in particular from 0 up to 30% by weight, preferablyfrom 0 up to 20% by weight, in particular from 0 to 15% by weight, basedon the total weight of the thermoplastic molding composition. In theevent that component K involves stabilizers, the content of thesestabilizers is usually up to 2% by weight, preferably from 0.01 to 1% byweight, in particular from 0.01 to 0.5% by weight, based on the totalweight of the thermoplastic molding composition.

The amounts generally comprised of pigments and dyes are from 0 to 10%by weight, preferably from 0.05 to 7% by weight, and in particular from0.1 to 5% by weight, based on the total weight of the thermoplasticmolding composition.

Pigments for the coloring of thermoplastics are well known, see forexample R. Gächter and H. Müller, Taschenbuch der Kunststoffadditive[Plastics additives handbook], Carl Hanser Verlag, 1983, pages 494 to510. A first preferred group of pigments that may be mentioned are whitepigments, such as zinc oxide, zinc sulfide, white lead [2PbCO3.Pb(OH)₂], lithopones, antimony white, and titanium dioxide. Of thetwo most familiar crystalline forms of titanium dioxide (rutile andanatase), it is in particular the rutile form which is used for whitecoloring of the molding compositions of the invention. Black colorpigments which can be used according to the invention are iron oxideblack (Fe₃O₄), spinell black [Cu(Cr, Fe)₂O₄], manganese black (a mixturecomposed of manganese dioxide, silicon dioxide, and iron oxide), cobaltblack, and antimony black, and also particularly preferably carbonblack, which is mostly used in the form of furnace black or gas black.In this connection see G. Benzing, Pigmente für Anstrichmittel [Pigmentsfor paints], Expert-Verlag (1988), pages 78 ff.

Particular color shades can be achieved by using inorganic chromaticpigments, such as chromium oxide green, or organic chromatic pigments,such as azo pigments or phthalocyanines. Pigments of this type aregenerally commercially available.

Examples of oxidation retarders and heat stabilizers which can be addedto the thermoplastic compositions according to the invention are halidesof metals of group I of the Periodic Table of the Elements, e.g. sodiumhalides, potassium halides, or lithium halides, examples beingchlorides, bromides, or iodides. Zinc fluoride and zinc chloride canmoreover be used. It is also possible to use sterically hinderedphenols, hydroquinones, substituted representatives of said group,secondary aromatic amines, optionally in combination withphosphorus-containing acids, or to use their salts, or a mixture of saidcompounds, preferably in concentrations up to 1% by weight, based on thetotal weight of the thermoplastic molding composition.

Examples of UV stabilizers are various substituted resorcinols,salicylates, benzotriazoles, and benzophenones, the amounts generallyused of these being up to 2% by weight.

Lubricants and mold-release agents, the amounts of which added aregenerally up to 1% by weight, based on the total weight of thethermoplastic molding composition, are stearyl alcohol, alkyl stearates,and stearamides, and also esters of pentaerythritol with long-chainfatty acids. It is also possible to use dialkyl ketones, such asdistearyl ketone.

The molding compositions of the invention comprise, as preferredconstituent, from 0.1 to 2% by weight, preferably from 0.1 to 1.75% byweight, particularly preferably from 0.1 to 1.5% by weight, and inparticular from 0.1 to 0.9% by weight (based on the total weight of thethermoplastic molding composition) of stearic acid and/or stearates.Other stearic acid derivatives can in principle also be used, examplesbeing esters of stearic acid.

Stearic acid is preferably produced via hydrolysis of fats. The productsthus obtained are usually mixtures composed of stearic acid and palmiticacid. These products therefore have a wide softening range, for examplefrom 50 to 70° C., as a function of the constitution of the product.Preference is given to use of products with more than 20% by weightcontent of stearic acid, particularly preferably more than 25% byweight. It is also possible to use pure stearic acid (>98%).

The molding compositions of the invention can moreover also comprisestearates. Stearates can be produced either via reaction ofcorresponding sodium salts with metal salt solutions (e.g. CaCl₂, MgCl₂,aluminum salts) or via direct reaction of the fatty acid with metalhydroxide (see for example Baerlocher Additives, 2005). It is preferableto use aluminum tristearate.

The constituents of the thermoplastic molding composition of theinvention can be mixed in any desired sequence.

The molding compositions of the invention can be produced by processesknown per se, for example extrusion. The molding compositions of theinvention can by way of example be produced by mixing the startingcomponents in conventional mixing devices, such as screw-basedextruders, preferably twin-screw extruders, Brabender mixers, or Banburymixers, or else kneaders, followed by extrusion. The extrudate is cooledand comminuted. The sequence of mixing of the components can be variedand, for example, two or optionally three components can be premixed,but it is also possible to mix all of the components together.

Intensive mixing is advantageous in order to maximize homogeneity ofmixing. Average mixing times necessary for this are generally from 0.2to 30 minutes, at temperatures of from 280 to 380° C., preferably from290 to 370° C. The extrudate is generally cooled and comminuted.

The molding compositions of the invention feature good flowability, hightoughness, especially tensile strain at break and notched impactresistance, and high surface quality. The molding compositions of theinvention are therefore suitable for the production of moldings forhousehold items, or for electrical or electronic components, and alsofor moldings for the vehicle sector.

The thermoplastic molding compositions of the invention can be usedadvantageously for the production of moldings, of fibers, of films, ofmembranes, or of foams. Accordingly, the present invention furtherprovides moldings, fibers, films, membranes or foams comprising thethermoplastic molding compositions of the invention.

The examples below provide further explanation of the invention, withoutrestricting the same.

EXAMPLES

The intrinsic viscosity of the polybiphenyl sulfones was determined in1% strength N-methylpyrrolidone solution at 25° C.

The products obtained were pelletized at melt temperature 370° C. in atwin-screw extruder (ZSK 18). Processing to give test specimens tookplace at melt temperature 375° C. and mold temperature 160° C.

The tensile tests were conducted to ISO 527, and notched impactresistance was determined to ISO 179 1eA.

Flowability of the products was determined at 380° C. in a capillaryrheometer. The method is described by way of example in “PraktischeRheologie der Kunststoffe and Elastomere” [Practical rheology ofplastics and elastomers] VDI Verlag 1991, page 234 ff. The ratio ofviscosity at high (2000 Hz) and low shear rate (50 Hz) was evaluated.

The purity of the monomers used (4,4′-dichlorodiphenyl sulfone,4,4″-dihydroxybiphenyl) was more than 99.5%.

Various qualities of anhydrous K₂CO₃ were used. The average particlesize is volume-average particle diameter and was determined on asuspension of the particles in a mixture of chlorobenzene and sulfolane(60/40 parts by weight), using a Mastersizer 2000 particle measurementdevice.

Potash A: average particle size 61 μm

Potash B: average particle size 120 μm.

Comparative Example 1

A polybiphenyl sulfone was obtained via nucleophilic aromaticpolycondensation of 287.08 g (1.00 mol) of 4,4′-dichlorodiphenylsulfone, and 186.21 g (1.00 mol) of 4,4′-dihydroxybiphenyl, using 145.12g (1.05 mol) of potassium carbonate (potash A) in 1050 ml of NMP. Thismixture was kept at 190° C. for 1 hour. The mixture was then diluted byadding 975 ml of NMP. The suspension was then reacted with methylchloride (15 l/h) for 1 hour at 130° C. After cooling to 80° C., thesuspension was discharged, the solid constituents were removed byfiltration, and the polymer was isolated via precipitation in 1/9NMP/water. The product was carefully washed with water and then driedfor 12 h in vacuo at 120° C. The intrinsic viscosity of the product was110.3 ml/g, its glass transition temperature being 226° C. High meltviscosity prevented pelletization of the product.

Comparative Example 2

A polybiphenyl sulfone was obtained via nucleophilic aromaticpolycondensation of 287.08 g (1.00 mol) of 4,4′-dichlorodiphenylsulfone, and 186.21 g (1.00 mol) of 4,4′-dihydroxybiphenyl, using 145.12g (1.05 mol) of potassium carbonate (potash A) in 1050 ml of NMP. Thismixture was kept at 180° C. for 2 hours. The mixture was then diluted byadding 450 ml of NMP. The suspension was then reacted with methylchloride (15 l/h) for 1 hour at 130° C. After cooling to 80° C., thesuspension was discharged, the solid constituents were removed byfiltration, and the polymer was isolated via precipitation in 1/9NMP/water. The product was carefully washed with water and then driedfor 12 h in vacuo at 120° C. The intrinsic viscosity of the product was115.2 ml/g, its glass transition temperature being 226° C. High meltviscosity prevented pelletization of the product.

Comparative Example 3

A polybiphenyl sulfone was obtained via nucleophilic aromaticpolycondensation of 287.08 g (1.00 mol) of 4,4′-dichlorodiphenylsulfone, and 186.21 g (1.00 mol) of 4,4′-dihydroxybiphenyl, using 143.05g (1.035 mol) of potassium carbonate (potash A) in 1050 ml of NMP. Thismixture was kept at 190° C. for 2.16 hours. The mixture was then dilutedby adding 450 ml of NMP. The suspension was then reacted with methylchloride (15 l/h) for 1 hour at 130° C. After cooling to 80° C., thesuspension was discharged, the solid constituents were removed byfiltration, and the polymer was isolated via precipitation in 1/9NMP/water. The product was carefully washed with water and then driedfor 12 h in vacuo at 120° C. The intrinsic viscosity of the product was58.6 ml/g, its glass transition temperature being 225° C.

Comparative Example 4

A polybiphenyl sulfone was obtained via nucleophilic aromaticpolycondensation of 574.16 g (2.00 mol) of 4,4′-dichlorodiphenylsulfone, and 372.42 g (2.00 mol) of 4,4′-dihydroxybiphenyl, using 280.56g (2.03 mol) of potassium carbonate (potash A) in 2100 ml of NMP. Thismixture was kept at 180° C. for 6.25 hours. The mixture was then dilutedby adding 900 ml of NMP. The suspension was then reacted with methylchloride (15 l/h) for 1 hour at 130° C. After cooling to 80° C., thesuspension was discharged, the solid constituents were removed byfiltration, and the polymer was isolated via precipitation in 1/9NMP/water. The product was carefully washed with water and then driedfor 12 h in vacuo at 120° C. The intrinsic viscosity of the product was82.9 ml/g, its glass transition temperature being 227° C.

Comparative Example 5 Excess of DCDPS

A polybiphenyl sulfone was obtained via nucleophilic aromaticpolycondensation of 586.75 g (2.044 mol) of 4,4′-dichlorodiphenylsulfone, and 372.42 g (2.00 mol) of 4,4′-dihydroxybiphenyl, using 286.09g (2.07 mol) of potassium carbonate (potash A) in 2100 ml of NMP. Thismixture was kept at 180° C. for 6 hours. The mixture was then diluted byadding 900 ml of NMP. The suspension was then reacted with methylchloride (15 l/h) for 1 hour at 130° C. After cooling to 80° C., thesuspension was discharged, the solid constituents were removed byfiltration, and the polymer was isolated via precipitation in 1/9NMP/water. The product was carefully washed with water and then driedfor 12 h in vacuo at 120° C. The intrinsic viscosity of the product was72.8 ml/g, its glass transition temperature being 225° C.

Comparative Example 6 Excess of DCDPS

A polybiphenyl sulfone was obtained via nucleophilic aromaticpolycondensation of 586.75 g (2.044 mol) of 4,4′-dichlorodiphenylsulfone, and 372.42 g (2.00 mol) of 4,4′-dihydroxybiphenyl, using 286.09g (2.07 mol) of potassium carbonate (potash A) in 2100 ml of NMP. Thismixture was kept at 180° C. for 6 hours. The mixture was then diluted byadding 900 ml of NMP. The suspension was then reacted with methylchloride (15 l/h) for 1 hour at 130° C. After cooling to 80° C., thesuspension was discharged, the solid constituents were removed byfiltration, and the polymer was isolated via precipitation in 1/9NMP/water. The product was carefully washed with water and then driedfor 12 h in vacuo at 120° C. The intrinsic viscosity of the product was71.3 ml/g, its glass transition temperature being 225° C.

Example 7 Excess of 4,4′-dihydroxybiphenyl

A polybiphenyl sulfone was obtained via nucleophilic aromaticpolycondensation of 574.16 g (2.00 mol) of 4,4′-dichlorodiphenylsulfone, and 379.87 g (2.04 mol) of 4,4′-dihydroxybiphenyl, using 286.09g (2.07 mol) of potassium carbonate (potash A) in 2100 ml of NMP. Thismixture was kept at 190° C. for 6 hours. The mixture was then diluted byadding 900 ml of NMP. The suspension was then reacted with methylchloride (15 l/h) for 1 hour at 130° C. After cooling to 80° C., thesuspension was discharged, the solid constituents were removed byfiltration, and the polymer was isolated via precipitation in 1/9NMP/water. The product was carefully washed with water and then driedfor 12 h in vacuo at 120° C. The intrinsic viscosity of the product was71.2 ml/g, its glass transition temperature being 225° C.

Example 8 Excess of 4,4′-dihydroxybiphenyl

A polybiphenyl sulfone was obtained via nucleophilic aromaticpolycondensation of 574.16 g (2.00 mol) of 4,4′-dichlorodiphenylsulfone, and 379.87 g (2.04 mol) of 4,4′-dihydroxybiphenyl, using 286.09g (2.07 mol) of potassium carbonate (potash A) in 2100 ml of NMP. Thismixture was kept at 190° C. for 6 hours. The mixture was then diluted byadding 900 ml of NMP. The suspension was then reacted with methylchloride (15 l/h) for 1 hour at 130° C. After cooling to 80° C., thesuspension was discharged, the solid constituents were removed byfiltration, and the polymer was isolated via precipitation in 1/9NMP/water. The product was carefully washed with water and then driedfor 12 h in vacuo at 120° C. The intrinsic viscosity of the product was72.0 ml/g, its glass transition temperature being 225° C.

Example 9 Excess of 4,4′-dihydroxybiphenyl

A polybiphenyl sulfone was obtained via nucleophilic aromaticpolycondensation of 574.16 g (2.00 mol) of 4,4′-dichlorodiphenylsulfone, and 379.87 g (2.04 mol) of 4,4′-dihydroxybiphenyl, using 286.09g (2.07 mol) of potassium carbonate (potash B) in 2100 ml of NMP. Thismixture was kept at 190° C. for 8 hours. The mixture was then diluted byadding 900 ml of NMP. The suspension was then reacted with methylchloride (15 l/h) for 1 hour at 130° C. After cooling to 80° C., thesuspension was discharged, the solid constituents were removed byfiltration, and the polymer was isolated via precipitation in 1/9NMP/water. The product was carefully washed with water and then driedfor 12 h in vacuo at 120° C. The intrinsic viscosity of the product was72.0 ml/g, its glass transition temperature being 225° C.

TABLE 1 Example comp1 comp2 comp3 comp4 comp5 comp6 7 8 9 Cl content[ppm] 1400 1370 2200 1450 3050 3150 710 670 560 Solvent content [ppm]n.d. n.d. 120 100 110 120 100 60 80 Modulus of elasticity — — 2260 22602280 2270 2280 2260 2270 [MPa] Tensile strain at break [%] — — 33 47 2122 78 81 76 ISO 179 1eA [kJ/m²] — — 68 67 67 66 71 72 72 η(50 Hz)/η(2000Hz) — — 6.8 5.9 4.8 4.7 3.2 3.1 3.3

The process of the invention allows intrinsic viscosity to be controlledby way of reaction time (Examples 7 to 9). At the same time,surprisingly, the polybiphenyl sulfone polymers of the invention exhibita low ratio of viscosity at shear rate 50 Hz to viscosity at shear rate2000 Hz. The polybiphenyl sulfone polymers of the invention thereforehave advantageous flow behavior at low shear rates, and this isparticularly advantageous for shaping in molds.

The polybiphenyl sulfone polymers of the invention also feature acombination of low content of polymer-bonded chlorine, low residualsolvent content, and improved tensile strain at break.

1.-17. (canceled)
 18. A polybiphenyl sulfone polymer with less than 800ppm content of polymer-bonded chlorine as determined by atomicspectroscopy.
 19. The polybiphenyl sulfone polymer according to claim18, which is a polymerization product of at least one aromatic dihydroxycompound including 4,4′-dihydroxybiphenyl, and 4,4′-dichlorodiphenylsulfone, and the polymerization is carried out with a molar excess ofthe at least one aromatic dihydroxy compound in a solvent comprisingN-methylpyrrolidone.
 20. The polybiphenyl sulfone polymer according toclaim 19, wherein the polymerization includes a molar ratio of the atleast one aromatic dihydroxy compound to 4,4′-dichlorodiphenyl sulfoneof from 1.005 to 1.08.
 21. The polybiphenyl sulfone polymer according toclaim 20, wherein the at least one aromatic dihydroxy compound comprisesat least 80% by weight of the 4,4′-dihydroxybiphenyl.
 22. Thepolybiphenyl sulfone polymer according to claim 21, wherein the at leastone aromatic dihydroxy compound is 4,4′-dihydroxybiphenyl.
 23. Thepolybiphenyl sulfone polymer according to claim 19, wherein theN-methylpyrrolidone is the only solvent used in the polymerization. 24.The polybiphenyl sulfone polymer according to claim 18, wherein thepolymer-bonded chlorine content is from 400 ppm to 700 ppm.
 25. Thepolybiphenyl sulfone polymer according to claim 24 with a tensile strainat break of more than 50% in accordance with ISO
 527. 26. Thepolybiphenyl sulfone polymer according to claim 25, wherein the tensilestrain at break is from 76% to 81%.
 27. The polybiphenyl sulfone polymeraccording to claim 24 with a modulus of elasticity in the range from2260 MPa to 2280 MPa.
 28. The polybiphenyl sulfone polymer according toclaim 24 with a ratio of viscosity at shear defined by η(50 Hz)/η(2000Hz) of 3.1 to 3.3.
 29. A polybiphenyl sulfone polymer with apolymer-bonded chlorine content of from 400 ppm to 700 ppm, asdetermined by atomic spectroscopy, a tensile strain at break of morethan 50% in accordance with ISO 527, and a ratio of viscosity at sheardefined by η(50 Hz)/η(2000 Hz) of 3.1 to 3.3.
 30. The polybiphenylsulfone polymer according to claim 30, which is a polymerization productof at least one aromatic dihydroxy compound including4,4′-dihydroxybiphenyl, and 4,4′-dichlorodiphenyl sulfone, and thepolymerization is carried out with a molar excess of the at least onearomatic dihydroxy compound in a solvent comprising N-methylpyrrolidone.31. A thermoplastic molding composition comprising the polybiphenylsulfone polymer of claim
 18. 32. The thermoplastic molding compositionof claim 31, further comprising a polymer selected from polyethersulfone (PES), polysulfone (PSU), polyetherimides, polyphenylenesulfides, polyether ether ketones, polyimides, and poly-p-phenylenes.33. A molding, fiber, film, membrane, or foam comprising thethermoplastic molding composition of claim 31.